Tactile marker

ABSTRACT

A tactile marker that is formed at least predominantly from a plastics material and which comprises a head portion that is arranged to sit, in use, on a walkway surface and a depending stem that is formed integrally with the head portion and is arranged in use to locate as a press fit within a hole in the walkway. The depending stem is formed along at least a portion of its length with a plurality of barbs, and each barb has a generally annular land and a generally conical portion formed integrally with the land. The generally conical portion has a cross-section that reduces in diameter in a direction away from the head portion.

This application is a National Stage completion of PCT/AU2009/000247filed Feb. 27, 2009, which claims priority from Australian patentapplication serial no. 2008 901075 filed Mar. 5, 2008.

FIELD OF THE INVENTION

This invention relates to a tactile marker of a type that is positionedon a walkway surface for the assistance of pedestrians generally and, inone of its applications, for the assistance of persons with impairedvision.

Such markers (which are known also as tactile ground surface indicators)typically are arrayed in a grid pattern to mark some sort of transition,for example at the foot or head of a stairway, at the loading area of anescalator or traveling footway and along the edge of a railway platform.However, it will be understood that the tactile marker may be used inother situations, for example as lane markers and boundary markers.Therefore, in the context of the present invention the term “walkway” isto be understood as embracing pedestrian ways and vehicular passagewaysand roadways such as are capable of accommodating walkers.

BACKGROUND OF THE INVENTION

There basically are three different types of tactile marker. One is inthe form of a tile-like pad that is molded from a durable plasticsmaterial and which incorporates a square array of integrally moldedindividual markers. The pad in use is positioned within a recess in awalkway surface. The second comprises an individual marker that has astem portion that is forced into one of a grid of drilled holes in awalkway and an integrally molded enlarged head portion that sits on thewalkway surface. The third type is similar to the second, except that aplurality of aligned markers is molded integrally with a commondepending rail, and the rail is forced into one of a number of parallelchannels that is cut into the walkway.

The first type of marker suffers the disadvantage that a recess must beprovided in a new walkway surface or be cut into a pre-existing surfaceto accommodate the pad. Also, the pad presents less attractively than agrid of individual markers. The markers of the second type presentbetter as a grid of individual markers but, being molded from a plasticsmaterial, the stems sometimes are not adequately retained in the drilledholes. Various attempts have been made to profile the stems to providefor better force-fitted engagement in the drilled holes, but theplasticity and/or profile of the stems of prior art markers have or hasmilitated against long-term secure engagement. The third type of markeris perceived as being unsatisfactory in at least some situations, due tothe unavoidable displaying of the rail that interconnects all of themarkers in a given row. Also, in some situations, for example incarpeted floors, the cutting of slit-like channels is either impossibleor unacceptable.

SUMMARY OF THE INVENTION

Broadly defined, the present invention provides a tactile marker that isformed at least predominantly from a plastics material and whichcomprises a head portion that is arranged in use to sit on a walkwaysurface and a depending stem that is formed integrally with the headportion and is arranged in use to locate as a press fit within a hole inthe walkway. The depending stem is formed along at least a portion ofits length with a plurality of barbs, and each barb has a generallyannular land and a generally conical portion formed integrally with theland. The generally conical portion has a cross-section that reduces indiameter in a direction away from the head portion.

The marker in accordance with the present invention typically providesfor more secure retention in a drilled hole than has been obtained withknown prior art markers.

When, in use, the depending stem may be pressed or otherwise forced intoa hole, a peripheral portion of the land of each barb will be deflectedupwardly and inwardly, causing a tensile stress to be induced in theintegrally formed conical portion and a radially inward reactive forceto be exerted on the periphery of the barb by the surrounding wall ofthe hole. The magnitude of this reactive force may increase with anyattempt to withdraw the marker from the hole, this providing for secureanchoring of the marker in the hole.

The head portion of the tactile marker may have any shape, for example agenerally cylindrical or domed shape, that will be sensed, when walkedupon, as marking a transition from a smooth walking surface. However,the head portion desirably has a generally frusto-conical shape and,most desirably, has an upper surface that is formed with a plurality ofanti-skid projections. Such projections, when provided, may optionallybe in the form of small cylindrical projections or nodules.

The tactile marker may be moulded from any one of a number ofthermoplastic materials, including nylon, but desirably is moulded frompolyurethane.

Longitudinally extending splines may optionally be formed integrallywith the stem portion of the marker for the purpose of engaging with thesurrounding wall of the hole into which the stem is in use pressed.

The splines may be provided to inhibit rotational movement of the stemportion about its longitudinal axis.

The peripheral margin of at least some of the barbs may be formed with aflat chordal region and such chordal regions may be displaced by 90° onsuccessive, adjacent barbs.

In one embodiment the barbs and the longitudinally extending splinesproject to approximately the same distance from an axis of the dependingstem, which may be solid.

For some, but not necessarily all, applications of the tactile marker, ametal cap may be provided to cover the head portion of the marker.

The metal cap may be formed from pressed metal and, also, be formed alsoover a major part of its surface area with a plurality of protuberancesas an alternative to the upper surface the head portion being formedwith the anti-skid projections.

The invention will be more fully understood from the followingdescription of an illustrative embodiment of the tactile marker. Thedescription is provided with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows a perspective view of the tactile marker,

FIG. 2 shows a view similar to that of FIG. 1 but with the tactilemarker rotated through approximately 45°,

FIG. 3 shows a sectional view of a stem portion of the tactile marker asseen in the direction of section plane 3-3 in FIG. 2,

FIG. 4 shows a sectional view of the stem portion of the tactile markeras seen in the direction of section plane 4-4 in FIG. 2, and

FIG. 5 shows an end view of the tactile marker as seen in the directionof arrow 5 in FIG. 2.

DETAILED DESCRIPTION OF A SPECIFIC EMBODIMENT OF THE INVENTION

As illustrated, the tactile marker comprises a generally frusto-conicalmarker head 10, having a bevelled surround 11 that extends to a marginalrim 12, and an integrally moulded stem 13 projecting downwardly from theunderside of the head 10. The tactile marker in accordance with theexemplified embodiment is formed entirely from a thermoplastics materialsuch as polyurethane and the head portion is arranged in use to sit on awalkway surface (not shown) with the depending stem located as a pressfit within a hole in the walkway.

The upper surface of the head portion 10 is provided with a plurality ofintegrally formed anti-skid projections 14 which, as illustrated, are inthe form of small cylindrical projections.

The stem 13 is formed along its length with five axially spaced barbs 15to 19, the lowermost one of which comprises a generally conical endportion of the stem 13. Also, the stem is formed between the uppermostbarb 15 and the underside of the head portion 10, with fourlongitudinally extending splines 20.

Each of the barbs 15 to 19 comprises a generally annular land 21 havingan outer peripheral margin 22 and, formed integrally with the land, agenerally conical portion 23. The conical portion associated with eachof the lands 21 is, as shown, located below the land and has a majordiameter that is the same as (or approximately equal to) that of theland, and the conical portion 23 has a cross-section that reduces indiameter in a direction away from the head portion 10.

The dimensions of the various parts of the tactile marker will bedetermined by particular applications to which the marker might be put.However, in one embodiment of the marker the barbs 15 to 19 may have anoutside diameter of 9.5 mm and the depending stem will in use be pressedor otherwise forced into a drilled hole having a diameter within therange 8.0 mm to 8.5 mm. As indicated previously, with such aninterference fit, when, in use, the depending stem is pressed into thehole, a peripheral portion of the land 21 of each of the barbs will bedeflected upwardly and inwardly, to cause a tensile stress to be inducedin the conical portion 23 and a radially inward reactive force to beexerted on the peripheral margin 22 of the barb by the surrounding wallof the hole. Thus, the stem 13 will be held captive against longitudinaldisplacement from the hole by the barbs 15 to 18 and will be heldcaptive against rotation within the hole by the splines 20. The splinedregion of the stem has the same effective diameter as the barbs and,thus, also engages with an interference fit in the hole.

Also, in order to enhance retention of the stem in the hole, an adhesivemay in some circumstances be inserted into the hole before the stem isinserted. Then, in order that the adhesive, when used, might flow alongthe full length of the stem and provide for maximum anchorage, the land21 of each of the barbs is formed with two diametrically disposed flatchordal regions 24, and the chordal regions are displace by 90° onsuccessive adjacent barbs.

In the claims which follow and in the preceding description of theinvention, expect where the context requires otherwise due to expresslanguage or necessary implication, the word “comprise” or variationssuch as “comprises” or “comprising” is used in an inclusive sense, i.e.to specify the presence of the stated feature but not to preclude thepresence or addition of further features of the invention.

1-14. (canceled)
 15. A tactile marker formed at least in part from aplastics material, the tactile marker comprising: a head portion beingarranged to sit on a walkway surface and a depending stem being formedintegrally with the head portion and being arranged to be located as apress fit within a hole in the walkway, the depending stem comprisingformed integrally and longitudinally extending splines for engaging witha surrounding wall of the hole into which the stem is pressed duringuse, the depending stem being formed, along at least a portion of itslength, with a plurality of barbs, and each barb having: a generallyannular land; and a generally conical portion formed integrally with theland and having a cross-section that reduces in diameter in a directionaway from the head portion.
 16. The tactile marker according to 15,wherein each of the plurality of barbs and the longitudinally extendingsplines approximately project a same distance from an axis of thedepending stem.
 17. The tactile marker according to 15, wherein thesplines are arranged to inhibit rotational movement of the stem portionabout its longitudinal axis.
 18. The tactile marker according to 15,wherein the depending stem is solid.
 19. The tactile marker according to15, wherein the head portion of the tactile marker has a generallyfrusto-conical shape.
 20. The tactile marker according to 15, whereinthe head portion of the tactile marker has an upper surface that isformed with a plurality of anti-skid projections.
 21. The tactile markeraccording to 20, wherein the projections are in the form of one ofcylindrical projections or nodules.
 22. The tactile marker according to15, wherein the tactile marker is moulded from a thermoplastic material.23. The tactile marker according to 15, wherein the tactile marker ismoulded from polyurethane.
 24. The tactile marker according to 15,wherein a peripheral margin of at least some of the plurality of barbsis formed with a flat chordal region.
 25. The tactile marker accordingto 24, wherein the chordal regions are displaced by 90° on successive,adjacent barbs.
 26. The tactile marker according to 15, wherein a metalcap is provided to cover the head portion of the tactile marker.
 27. Thetactile marker according to 26, wherein the metal cap is formed frompressed metal.
 28. The tactile marker according to 26, wherein the metalcap is formed over a major portion of its surface area with a pluralityof protuberances as an alternative to the upper surface the head portionbeing formed with the anti-skid projections.
 29. The tactile markeraccording to 27, wherein the metal cap is formed over a major portion ofits surface area with a plurality of protuberances as an alternative tothe upper surface the head portion being formed with the anti-skidprojections.
 30. The tactile marker according to 15, wherein the tactilemarker is moulded from nylon.